A switch mode power supply (SMPS) may operate by using either pulse-width modulation (PWM) or pulse-frequency modulation (PFM) control to the power switching transistor(s). PWM operation of the SMPS is efficient during higher load conditions but drops off in efficient operation under light load condition. PFM control results in higher efficiency of the SMPS during light load conditions, but results in less efficiency at higher load conditions. High efficiency is important in a SMPS especially when used in battery powered applications. FIG. 12 shows a graph of typical efficiencies of an SMPS over a range of output load currents when using PFM or PWM control.